\section{Evaluated techniques}

\subsection{\quonto}

\quonto is... \cite{Calvanese2007}.

\subsection{\requiem}

\requiem is the implementation of the conjunctive query rewriting algorithm presented in \cite{Perez-Urbina2008}. The algorithm considers constraints modeled with the DL $\ELHI$ and it is \emph{optimal} for the spectrum of DLs with data complexity of query answering ranging from \PTime-complete to \LogSpace. If $R$ is expressed in a \PTime-complete DL, then $Q'$ is a datalog query; if $R$ is expressed in an \NLogSpace-complete DL, then $Q'$ consists of a union of conjunctive queries and a linear datalog query; finally, if $R$ is expressed in a \LogSpace DL, then $Q'$ is a union of conjunctive queries.